1. Field of the Invention
The present invention relates to an exposure control device for a camera. In particular, it relates to an exposure control device having a light measuring means for obtaining an average light measurement corresponding to a brightness of an entire scene to be photographed and a means for obtaining a spot light measurement corresponding to a brightness of a part of the scene, in which either the average or the spot light measurement is optionally selected.
2. Description of the Related Art
AE (automatic exposure) lock photography is often used when a part having a greatly different brightness is present in the scene to be photographed. In AE lock photography, the brightness of a desired part of the scene to be photographed is measured and stored regardless of a shutter release operation, and an exposure control is performed based on the stored spot light measurement. To achieve this combination of a spot light measurement and AE lock mode, the specification of U.S. Pat. No. 4,589,757 proposes an exposure control device in which a mode is automatically changed from a non-AE lock mode to an AE lock mode when a switch for carrying out a spot light measurement is manually operated. In this device, although a user is aware that a spot light measurement should be performed while in the AE lock mode, a great deal of skill is required to determine whether the average light measurement or the spot light measurement should be adopted for the scene to be photographed. Accordingly, where an AE-locked operation based on a spot light measurement is necessary, for a non-skilled beginner, the sequential operation of performing an AE lock prior to a shutter release operation is more easy than the operation of depressing the spot light measurement button switch after the necessity for a spot light measurement is determined, as in the conventional technique. Moreover, an exclusive AE lock changeover means is not provided in the conventional device, and thus, when the spot light measurement button switch is not operated, the average light measurement is automatically selected. However, in this state, an AE lock cannot be performed, and accordingly, operation of the conventional device is difficult for beginners. Moreover, the average light measurement is always performed for flash photography (the spot light measurement is not allowed), and AE-locked operation cannot be carried out.